Sheet feeding machine



March 1941- H. T. BACKHOUSE 2,236,363

SHEET FEEDING MACHINE Filed March 50, 1939 2 Sheets-Sheet 1 WeakerJud/7'00 a/f We a/rer Or/ve INVENTOR. v 6.155045 r iwzv'aslvofine/(Haas:

ATTORNEYS Patented Mar. 25, 1941 PATENT OFFICE I SHEET FEEDINGMAC'HINEHeadley Townsend Backhouse, London,- England Application thi ned, 1939,Serial No. 265,007

I In Great Britain April 1, 1938 7 Claims.

The invention comprises improvements in or relating to sheet-feedingmachines and is 'concemed with stream feeders of the kind (hereinafterreferred to as the kind described) in which sheets of paper or the likeare separated and partly forwarded from the top of a stack by meansoperating to grip and lift the sheets at or near (1. e. within the rearhalf of the sheets) the rear edges thereof and in which the sheets arethen removed (e. g. to a printing machine), by conveyor elementsengaging the'front edge of the sheets, in the form of a continuousstream of partly underlapping sheets. a stream feeder of this kind'isdescribed in U. S. Patent No. 2,108,702 and the present invention isparticularly suitable for application to stream feeders as described inthat patent.

In machines of the kind described the position of the rear edge of eachsheet as it is lifted from the stack and forwarded towards the conveyoris accurately determined by the separating and forwarding means engagingthe sheet at or near the rear edge. The exact position of the front edgeof the sheet is, on the other hand, indeterminate because the sheets, asthey are lifted from the stack, sag or, if an air blast is used underthe sheets to assist separation, billow by varying amounts. It is,however, the front edge of the sheet which is taken first by theconveyor and which determines the position of the sheet on the conveyorin relation to the preceding and succeeding sheets and the difficultytherefore arises that the sheet may be misplaced on the conveyor inspite of the fact that the position of its rear edge is accuratelycontrolled. It is an object of the present invention to provide amachine of the kind described in which this difficulty is largelyreduced or overcome.

The invention consists in a machine of the kind described having asuction or equivalent gripper arranged to grip the underside of eachsheet at or near the front edge after the sheet has been separated fromthe stack and in which the sheet is tautened from front to rear byrelative movement away from one another in the direction of feeding andwhile gripping the sheet of the suction or equivalent gripper aforesaidand the means gripping the rear of the sheet, the potential movementbeing in excess of that required to tauten a sheet with normal amount ofsag in order to be able to tauten sheets with abnormal sag and themachine being so constructed and arranged that when the sheet is tautthe relative movement aforesaid ceases or One example of the suction orequivalent gripper slips on. the sheet without disturbing the accuratepositioning of the sheet by the means gripping the rear of the sheet.

The relative movement of the suction or equivalent gripper engaging thefront of the sheet and the means gripping the rear of the sheet may beeffected by movement of the rear gripping means in the backwardsdirection or by moving the front gripper in the forwarding directionwhile maintaining the rear gripping means stationary. It is, however,preferred to effect the relative movement while both gripping means aremoving in the forwarding direction, the front gripping means movingfaster than the rear gripping means.

In the preferred form of the invention the front gripper also actsduring the preliminary separation of the uppermost sheet as a frontgauge or stop preventing creeping forward of the top sheets.

The front gripper, when it is a suction device, may be in the form of atube extending transversely of the stack and having suction orifices inits upper surface or it may be constituted by one or more suckerslocatedclose to the front of the stack and, when there are two or more suckers,spaced apart across the stack.

In one form of the invention parts of the suction device or othergripper adjacent opposite side edges of the stack are arranged forrelative movement, while gripping a sheet, in a direction transverse tothe feeding direction to tauten the front edge of the sheet.

35 Four specific embodiments of the invention will now be described byway of example and with reference to the accompanying diagrammaticdrawings in which:

Figures 1 to 5 show five successive positions in the cycle of operationsof the front gripper in one embodiment;

Figure 6 is a section illustrating a second embodiment;

Figure 7 is a perspective view of the suction device employed in theembodiment shown in Figure 6;

Figure 8 is a side view partly in section illustrating a thirdembodiment;

Figure 9 is a section illustrating a fourth embodiment, and

Fig. 10 is a timing diagram showing the relative functioning of thefront and rear suckers and the blowers with respect to the forms of theinvention illustrated in Figs. 1 to 7 inclusive.

Like references indicate like parts in the several figures of thedrawings.

In each example the sheets are separated and forwarded from their rearedges by means of suckers operating over the top of the stack incombination with an air blast directed underneath the rear edge of eachuppermost sheet in turn, the arrangement being similar to that.described in U. S. Patent No. 2,108,702.

In the first example, which is illustrated in Figures 1 to 5,'thesuction device consists of a tube I having a cross-section in the formof a right-angled triangle. The tube extends transversely of the stack 2with one of its shorter sides 3 substantially vertical and the othershorter side 4 substantially horizontal. The horizontal side 4 isprovided at intervals along the length of the tube with orifices towhich suction may be applied through the tube.

During the operation of the machine the tube is given the followingcycle of movements, for example by means of cams, for each sheetseparated. At the beginning of the cycle the tube is located with itsvertical face in contact with the front of the stack and with itshorizontal face at a slightly higher level than the top of the stack sothat the tube acts as a front gauge or stop. The tube remains in thisposition (which is shown in Figure 1) during the initial separation ofthe rear edge of the uppermost sheet. As soon as the rear edge has beenseparated, the tube drops vertically until its upper surface issubstantially level with the top of the stack as shown in Figure 2. Thefront'edge 5 of the separated sheet is fed over the tube by means of theforwarding suckers 20 and air blast nozzles 2| at the rear of the stackto the position shown in Figure 3 and the tube then returns to itsinitial position engaging, and if necessary lifting, the front edge ofthe sheet in doing so, this position being shown in Figure 4. Suction isthen applied to the tube causing it to grip the underface of the frontedge of the sheet and the tube is moved in the forwarding directiontowards conveyor rollers 6 located a short distance in front of thestack. The tube moves in the forwarding direction at a greater speedthan the forwarding suckers at the rear of the sheet thereby tending tostretch or tauten the sheet from front to rear. The tube is of metal andthe suction orifices are so proportioned and the suction is of such astrength that as soon as the sheet has been tautened the extraresistance of its front edge to forwarding causes the sheet to slip onthe metal tube without moving the rear of the sheet in relation to therear forwarding suckers. The tube is moved in the forwarding directionuntil the front edge of the sheet is presented to the conveyor rollersand engaged by them (as shown in Figure 5) when the suction is releasedand the tube returned to the initial position, thereby completing thecycle. Throughout the whole of the movements of the tube its axisremains substantially horizontal.

In the second example, shown in Figures 6 and 7, the suction device isconstituted by a plurality of metal suckers I, say three, spaced apartacross the front edge of the stack and each in the form of a shortvertical tube of rectangular crosssection extending tangentially from ahorizontal suction tube 8. The cycle of movements of the suckers totauten and forward the sheets is similar to that of the triangular tubedes r b d above, but in this embodimentihe movements are eifected byvertical and rotational movements of the horizontal suction tube. At thecommencement of the cycle the rectangular sectioned sucker tubes lievertically against the front of the stack with their ends 9, whichconstitute the suckers, extending above the top of the stack to formfront stops as shown in Figure 6. As soon as the separation of the rearof the uppermost sheet has been effected the suction tube drops to theposition shown in dotted lines in the figure carrying with it thesuckers until the suckers are level with the top of the stack and thetube remains in that position until the front edge of the separatedsheet has been forwarded over the suckers. The suction tube then risesvertically to engage the suckers with the underface of the sheet and assoon as engagement has been effected is rotated about its axis to movethe suckers in the forwarding direction and to feed the front edge 5 ofthe sheet to the conveyor roller 6. To ensure that the suckers may havesufficient movement in the forwarding direction to present the sheetproperly to the conveyor rollers, the lower conveyor roller is providedwith circumferential grooves I0 into which the sucker tubes arereceived. As soon as the sheet has been engaged by the conveyor rollers,the suction is released and the horizontal suction tube rotated in thereverse direction to return the suckers to their initial position.

In Fig. 10 I have illustrated in a timing diagram the relative movementsof the front and rear suckers and of the air blast nozzles, as well asthe timing of the suction in the suckers and the .ir blast in the airblast nozzles. The diaram applies only to the two forms of the inventionthus far described. The arrows indicate that during the periods somarked movement is up or down. The words "up and down indicate thatduring the periods to which they are applied the part in questionremains up or down, as the case may be. The speed of the suckers inmoving forward and backward is not indicated on the diagram, but aspreviously stated the forward travel of the front suckers is faster thanthat of the rear suckers, with the result that they separate relatively,as indicated by the fact that the distance a in Fla. 4 is increased to11+ in Fig. 5.

In the third example shown in Figure 8, the suction device is in theform of a cylindrical suction tube II on which a closely fitting outertube I2 is mounted, the outer tube being rotatable on the suction tubeand having a succession of apertures i3 which, when the tube is turnedsuccessively register with corresponding apertures II (which may beslots or holes) on the upper surface of the inner suction tube. Thetubes lie horizontally against the front edge of the stack and at thebeginning of the cycle with their upper surface slightly above the levelof the top of the stack as shown in Figure 8. In the operation of thedevice the outer tube I2 is rotated intermittently or continuously inthe direction such that its upper surface moves in the feeding directionof the sheets and suction is applied through the apertures in the innertube to each aperture ii in the outer tube as it moves into registerwith an aperture N in the inner tube. As the front edge of each sheet isfed forwardly by the rear forwarding suckers, it is engaged by therotating outer tube and ripped and released by the apertures as suctionis applied to them as they move into and out of register with theapertures in the inner tube. The forward rotation of the outer tubefeeds the sheet at a greater rate than the forwarding suckers move therear edge of the sheet thereby tending to stretch or tauten the sheet,but, as in the previous examples, the grip of the roller on the sheetsis insufficient, to cause the sheets to slip in relation to the reargrippers. The roller in this example has an up and down movement similarto that of the tube in the first example but it does not movebodily 7towards and away from the conveyor rollers.

According to the fourth example, shown in Figure 9, the lower conveyorroller 6 is provided with one or more circumferential grooves 15 and asuction tube It is provided for each groove extending between therollers and received within the groove. The suction tube is supportedfrom a horizontal tube I! located in front of the conveyor rollers andis formed at its rear-end with a. horizontal sucker mouth l8. The suckermouth is moved, by movement of the tube in the groove of the conveyorroller, in the forwarding andreturn directions only.

When the front edge of the uppermost sheet has been forwarded from thetop of the stack it is engaged on its underface by the sucker mouth l8.and is drawn forwardly towards the conveyor rollers at a greater speedthan the rear of the sheet is forwarded, thereby stretching or tauteningthe sheet. As in the previous embodiments the sucker mouth is arrangedto slip on the sheet when it has been tautened but in this case thesucker is arranged to draw the sheet, while slipping on it, between theconveyor rollers. The sucker mouth then releases the sheet and isreturned underneath the sheet to its initial position close to the frontof the stack. In this embodiment the suction device does not act as afront stop and it is preferred, therefore, to employ the usual form ofpivoted front stop IS in addition to the sucker.

It is to be understood that in each of the above embodiments the suctiondevices may be so modified that they grip the sheet adjacent to itsopposite side edges and while gripping the sheet they may be moved awayfrom one another transverse to the feeding direction to tauten the frontedge of the sheet in addition to their movement to tauten the sheet fromfront to rear as described above.

In each of the examples described above the tautening of the sheet fromfront to rear is effected by movement of the front suction gripper at aspeed greater than that of the rear suction gripper, the front gripperslipping on the sheet when it has been tautened. It is however, withinthe scope of the invention to arrange the machine in such manner thatafter suflicient relative movement of the front and rear grippers hastaken place to tauten any sheet likely to be found in practice (with thenecessary slip for sheets which have not the maximum amount of sag) therear gripper releases the sheet which v is then carried forward by. thefrontgripper pers remain stationary) and the rear grippers then releasethe sheet and return to their initial position to grip the next sheetand to carry out their second cycle. The completion of the forwarding ofthe sheet to the conveyor is effected by the front grippers which moveforwards to present the sheet to the conveyor during the time that theback grippers are engaging and lifting the next sheet.

Further, in each of the above examples the front gripper has beenarranged to slip on the sheet when a sheetwith normal sag has beentautened. It is however within the invention so to arrange the machinethat as soon as the sheet has been tautened relative movement betweenthe front and rear grippers ceases. This may, for example, be effectedby providing. a resilient connection between the front gripper and itsoperating means so arranged that the additional resistance to movementexperienced by the gripper when the sheet is taut causes the connectionto give. Alternatively the operating means for the front gripper mayconsist of a cam arranged to eflect the'rearward movement of the gripperpositively by engagement with a follower and against the action of aspring which tends to maintain the follower in contact with the roller.The forward movement of the gripper is effected by the spring which isonly strong enough to tauten the sheets so that as soon as the sheetsare taut the follower leaves the cam and further relative movement ofthe rippers ceases.

It is further to be understood that it is an important advantage of themechanism herein described that any lack of parallelism between, thefront and back edges of the sheets due to sag or the like is removed bythe tautening of the sheets from front to rear,.thereby ensuring thatthe sheets are taken by the conveyor in the cor rect angularrelationship, and that the relative slip between the sheets and thefront grippers contributes largely to this result since differentamounts of slip may take place at opposite sides of the sheets and,consequently, the opposite sides may be tautened until each side reachesthe desired degree of tautness.

I claim:

1. In a machine for feeding sheets from the top of a pile, rear suckermeans adapted to grip the uppermost sheet and move forward therewith,forward sucker means arranged in front of the pile adapted to grip thesurface of the advanced sheet and move forwardly more rapidly than therear sucker means, the grip of the rear sucker means being strong enoughrelatively to prevent slippage between the sheet and said rear suckermeans.

2. In a machine for feeding sheets from the top of a pile, rear suckermeans adapted to grip the uppermost sheet, raise it and move it forward,forward sucker means arranged in front of the pile adapted to moveupwardly, grip the lower surface of the advanced sheet and moveforwardly more rapidly than the rear sucker means, the grip of the rearsucker means being stronger than that of the forward sucker means inorder that slippage may occur between the sheet and the forward suckermeans after the sheet has been tautened.

3. In a machine for feeding sheets from a pile, feed rollers adapted toreceive sheets from the top of the pile and move them forward, suckermeans at the rear of the pile for gripping and raising the uppermostsheet and advancing it in the direction of feed, air blast means forraising the forward portion of the gripped sheet from the pile; forwardsucker means located in front of the pile adapted to grip the undersurface of the raised and advanced sheet and to mov forward at a speedin excess of the forward speed of the rear sucker means, the sheetforwarding effect of said forward sucker means being weaker than thesheet forwarding effect of said rear sucker means whereby the sheet istautened while control of the position of the sheet is maintained bysaid rear sucker means, said forward sucker means continuing itsforwarding impulse until the sheet is in the grip of said feed rollers.

4. In a machine for feeding sheets from a pile, feed rollers adapted toreceive sheets from the top of the pile and move them forward, suckermeans at the rear of the pile for gripping and raising the uppermostsheet and advancing it in the direction of feed, air blast means forraising the forward portion of the gripped sheet from the pile, pilegauging means at the front of the pile, the said pile gauging meansbeing hollow and constituting a suction conduit having openings at itsupper edge, the pile gauging means being adapted to grip the undersurface of the raised and advanced sheet, to move forwardly at a speedin excess of the forward movement of said rear sucker means, and toexert a forwarding effect on the sheet weaker than that of the rearsucker means thereon, whereby the forward edge of the uppermost sheet isheld against movement by said pile gauging means until the blast raisesthe sheet above the level of the pile and whereby the sheet is tautenedafter it is gripped by the pile gauging means, said pile gauging meanscontinuing its forward impulse until the sheet is in the grip of saidrollers.

5. In a machine of the class described, pile gauging means having a flatrear surface for engagement with a pile and being hollow in order toserve as a suction conduit, said hollow gauging means having suctionopenings at its upper end, and said gauging means being arranged andactuated to permit the uppermost sheet to advance somewhat beyond theforward end of the pile after which the gauging means grips the undersurface of said advanced sheet and carries it forward away from thepile.

6. In a machine of the class described, pile gauging means having a flatrear surface for engagement with a pile and being hollow in order toserve as a suction conduit, said hollow gauging means having suctionopenings at its upper end and having movement up and down and forwardand backward, said gauging means when lowered permitting the uppermostsheet to advance somewhat beyond the forward end of the pile after whichsuction is exerted to cause the gauging means to grip the under surfaceof the advanced sheet and whereby the forward movement of the gaugingmeans carries the sheet forward for feeding purposes.

7. In a machine of the class described, pile gauging means having a flatrear surface for engagement with the pile and having an upper surfacenormally standing somewhat above the level of the pile, said gaugingmeans being hollow in order to serve as a suction conduit and havingsuction openings in its upper surface, said gauging means moving down tosubstantially the level of the pile for permitting the uppermost sheetto be advanced over the gauging means, and then moving upwardly to gripthe under surface of the sheet by suction and forwardly to furtheradvance the sheet, and then with it suction broken moving backwardly toits normal position against the pile.

HEADLEY TOWNSEND BACKHOUSE.

